Native and Invasive Native and Invasive PlantsPlants

Invasive plant Invasive plant • Ability to spread aggressively

outside its natural range• Especially in new habitat

Invasive plant Invasive plant • Lack insects, diseases and

foraging animals

Where are they a Where are they a problem?problem?Disrupted habitats•Thrive on disturbed sites like construction areas and road cuts

Why are they a problem?Why are they a problem?• Threaten native plants and

animals• Insects, micro-organisms, birds,

etc…• Alter habitats and reduce

biodiversity

Native PlantsNative Plants

Plants growing here for a long time>500 years

◦Christopher Columbus (1492)

Native Plant DatabasesNative Plant Databaseshttp://www.se-eppc.org/southcar

olina/http://www.scnps.org/http://www.namethatplant.net/http://www.wildflower.org/

collections/collection.php?start=0&collection=SC&pagecount=10&pagecount=100

BiodiversityBiodiversityThe diversity of animals is linked

to the diversity of plants◦Greater number of plant species

means less competition and increased niches

BiodiversityBiodiversity2.5 acres of Amazonian rainforest

supports 473 species of treesOnly 134 species of trees in

Pennsylvania

BiodiversityBiodiversity

Trophic level is the position an organism occupies in food chain.First trophic level: PlantsPlants capture sun’s energy and

turn it into food for the rest of us

BiodiversityBiodiversity

Second trophic level: HerbivoresTransfer energy from plants to predators and parasites in higher trophic levels

◦Mainly insects

BiodiversityBiodiversityWorldwide, 37% of animal

species are herbivorous insectsPound for pound, insects contain

more protein than beef96% of birds rely on insects and

spiders to feed young

Keystone SpeciesKeystone SpeciesKeystone species essential role in maintaining diversity◦Robert T. Paine research

Tidal pool on Pacific Coast◦Simple ecosystem

Keystone SpeciesKeystone Species

Simple Ecosystem◦Rivet example

Some rivets on airplane more important than others◦Seat versus engine

Keystone SpeciesKeystone Species

Simple EcosystemRemoving some species had little effect on populations of remaining speciesBut removal of a predatory starfish (Pisaster ochraceus) caused a collapse of half the remaining species’ population

Keystone SpeciesKeystone SpeciesComplex SystemNo central players

◦Jenga exampleHow vital a block’s role to the tower’s stability is based on the presence of other blocks

Keystone SpeciesKeystone Species

Complex SystemEvery time block is removed, role and importance of other blocks changesAlmost any species can be a keystone species depending on circumstances

Trophic CascadesTrophic CascadesThe impact on other species when removing a keystone species

◦Predator exampleYellowstone wolf population reducedMoose spend less time looking around

◦More time grazingOvergrazing led to erosion, impacting streams, fish, plants, etc.http://www.twp.org/

Non-Native (Alien)Non-Native (Alien)Aliens colonize areas faster than

nativesAlien plants interact minimally

with ecosystem and pass along very little energy to herbivores (2nd trophic level)

Non-Native (Alien)Non-Native (Alien)“Pest-free” ornamentals are

primarily selected for landscapeIt takes time for insects to adapt

to specific chemical composition of leaves

Non-Native (Alien)Non-Native (Alien)Paperbark tea

tree introduced to Everglades in 1900

Presently, 8 species of arthropods feed on leaves, opposed to 409 back in Australia

Non-Native (Alien)Non-Native (Alien)90% of herbivorous insects are

specialists that have evolved with a plant

Non-Native (Alien)Non-Native (Alien)Insects develop ability to

overcome physical and chemical defenses of host, but limited to feed on that host only◦Mainly due to leaf chemistry

Insects develop enzymes that detoxify chemistry

Non-Native (Alien)Non-Native (Alien)Tannins in oak leaves would bind

protein if we eat them, starving us

Lima beans contain cyanide unless boiled

Cucumber leaves are lethal

Non-Native (Alien)Non-Native (Alien)10% of insect

herbivores are generalists that eat several types of plants

Ability to produce very powerful gut enzymes called mixed-function oxidases

Feed on many alien plants, but not enough

Non-Native (Alien)Non-Native (Alien)

Compare diversity and biomass of insects on 4 woody natives versus 5 aliensNative plants produce 4x more biomassSupported 3.2x more species

Non-Native (Alien)Non-Native (Alien)

Compare diversity and biomass of insects on 4 woody natives versus 5 aliensIn terms of caterpillars (most important to birds), 35x more than alien plantsNatives produced 2x as many generalists

Non-Native (Alien)Non-Native (Alien)A plant can become

native regardless of origins

Norway maple introduced from Europe in 1756Still has few insect

feedersCompare to 80 millions

years of coevolution, 250 years isn’t much

Non-Native (Alien)Non-Native (Alien)Native applies to local regionsHuman influence is too rapid for

adaption

Non-Native (Alien)Non-Native (Alien)Birds eat fruit after reproductionMost species depend on insect

protein for egg laying and feeding young and nesting

Non-Native (Alien)Non-Native (Alien)

Non-invasive qualities of alien does not make it nativeClematis vitalba introduced 100 years agoSupports 40 herbivores in homeland but only 1 after 100 years since introduction here

http://www.wildflower.org/collections/

http://www.wildflower.org/collections/collection.php?start=0&collection=SC&pagecount=10&pagecount=100

http://www.se-eppc.org/http://www.dnr.sc.gov/

invasiveweeds/illegal1.htmlhttp://www.scnps.org/

http://arstechnica.com/science/2013/03/by-building-fairy-circles-termites-engineer-their-own-ecosystem/

Fragmentation Biological Dynamics of Forest Fragments Project

Island ecosystem stabilityhttp://www.stri.si.edu/english/

research/facilities/affiliated_stations/bdffp/